Part way through composing a Text Message if you try to add an additional recipient there is no option to. (as you can on the menu option "add recipient" on a 8120)

You can select Blackberry Options when in the Text Message and select show recipients when typing a Text Message , but when you click OK the text message has disappeared and is saved as a draft, so if you want to add further recipients you have to create a new message with them on it from the start?